This K02 application out-lines research and career development plans to investigate the role of sleep regulation in the developmental psychobiology of affective disorders. The first goal is to extend a well-established line of research based on measures of EEG sleep and cortisol in child and adolescent depression by investigating: (1) abnormalities in sleep and cortisol regulation focusing on the sleep-onset transition; (2) normal maturational changes in sleep and cortisol regulation relevant to these abnormalities; and (3) the predictive validity of sleep and cortisol abnormalities in longitudinal clinical follow-up. The second goal is to further develop and investigate a larger developmental model of sleep regulation. The model emphasizes close links between sleep regulation and neurobehavioral systems involved in the regulation of affect and arousal which are modulated in regions of prefrontal cortex (PFC). Matur-ational changes in PFC-subcortical circuits influencing sleep, arousal, and affect are hypothesized to contribute to sleep changes associated with depression, particularly near the transition from wakefulness into sleep. Based on this model, predictions are made regarding sleep changes in the development of affective disorders and effects of sleep deprivation of affective regulation. The long-term goal of this work is to understand mechanisms of dysregulation which may lead to more effective treatment of early onset affective disorders. Career development activities to support these goals are described. Further advancing this line of investigation will require increased knowledge and skills in four areas: the development of affect regulation; the relevant neurocircuitry and its development; more direct measures of the neural systems of interest; and statistics. The candidate will pursue these goals through course work, focused readings, and supervised learning experiences and collab-orations with scientists locally and nationally.